.\" $NetBSD: pathconf.2,v 1.2 1995/02/27 12:35:22 cgd Exp $ .\" .\" Copyright (c) 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93 .\" .Dd June 4, 1993 .Dt PATHCONF 2 .Os BSD 4 .Sh NAME .Nm fpathconf , .Nm pathconf .Nd get configurable pathname variables .Sh SYNOPSIS .Fd #include <unistd.h> .Ft long .Fo fpathconf .Fa "int fildes" .Fa "int name" .Fc .Ft long .Fo pathconf .Fa "const char *path" .Fa "int name" .Fc .Sh DESCRIPTION .Pp The .Fn pathconf and .Fn fpathconf functions provides a method for applications to determine the current value of a configurable system limit or option variable associated with a pathname or file descriptor. .Pp For .Nm pathconf , the .Fa path argument is the name of a file or directory. For .Nm fpathconf , the .Fa fildes argument is an open file descriptor. The .Fa name argument specifies the system variable to be queried. Symbolic constants for each name value are found in the include file .Li <unistd.h> . .Pp The available values are as follows: .Pp .Bl -tag -width "123456" .Pp .It Li _PC_LINK_MAX The maximum file link count. .It Li _PC_MAX_CANON The maximum number of bytes in terminal canonical input line. .It Li _PC_MAX_INPUT The minimum maximum number of bytes for which space is available in a terminal input queue. .It Li _PC_NAME_MAX The maximum number of bytes in a file name. .It Li _PC_PATH_MAX The maximum number of bytes in a pathname. .It Li _PC_PIPE_BUF The maximum number of bytes which will be written atomically to a pipe. .It Li _PC_CHOWN_RESTRICTED Return 1 if appropriate privileges are required for the .Xr chown 2 system call, otherwise 0. .It Li _PC_NO_TRUNC Return 1 if file names longer than KERN_NAME_MAX are truncated. .It Li _PC_VDISABLE Returns the terminal character disabling value. .It Li _PC_XATTR_SIZE_BITS Returns the number of bits used to store maximum extended attribute size in bytes. For example, if the maximum attribute size supported by a file system is 128K, the value returned will be 18. However a value 18 can mean that the maximum attribute size can be anywhere from (256KB - 1) to 128KB. As a special case, the resource fork can have much larger size, and some file system specific extended attributes can have smaller and preset size; for example, Finder Info is always 32 bytes. .El .Sh RETURN VALUES If the call to .Nm pathconf or .Nm fpathconf is not successful, \-1 is returned and .Va errno is set appropriately. Otherwise, if the variable is associated with functionality that does not have a limit in the system, \-1 is returned and .Va errno is not modified. Otherwise, the current variable value is returned. .Sh ERRORS If any of the following conditions occur, the .Nm pathconf and .Nm fpathconf functions shall return -1 and set .Va errno to the corresponding value. .Bl -tag -width ENAMETOOLONGAA .\" =========== .It Bq Er EINVAL The value of the .Fa name argument is invalid. .\" =========== .It Bq Er EINVAL The implementation does not support an association of the variable name with the associated file. .El .Pp .Fn Pathconf will fail if: .Bl -tag -width ENAMETOOLONGAA .\" =========== .It Bq Er EACCES Search permission is denied for a component of the path prefix. .\" =========== .It Bq Er EIO An I/O error occurs while reading from or writing to the file system. .\" =========== .It Bq Er ELOOP Too many symbolic links are encountered in translating the pathname. This is taken to be indicative of a looping symbolic link. .\" =========== .It Bq Er ENAMETOOLONG A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. .\" =========== .It Bq Er ENOENT The named file does not exist. .\" =========== .It Bq Er ENOTDIR A component of the path prefix is not a directory. .El .Pp .Bl -tag -width ENAMETOOLONGAA .Fn Fpathconf will fail if: .\" =========== .It Bq Er EBADF .Fa fildes is not a valid open file descriptor. .\" =========== .It Bq Er EIO An I/O error occurs while reading from or writing to the file system. .El .Sh SEE ALSO .Xr sysctl 3 .Sh HISTORY The .Nm pathconf and .Nm fpathconf functions first appeared in 4.4BSD.